1. Field of the Invention
This invention relates to a magnetic disk cartridge having a sliding shutter which covers a magnetic head opening formed in the casing of the magnetic disk cartridge and which, when open, gives the magnetic head access to the magnetic disk stored in the casing of the disk cartridge.
2. Description of the Prior Art
There has been known a magnetic disk cartridge which has a casing having a magnetic head opening through which a magnetic head gains access to a magnetic disk accommodated in the casing, and a shutter which slides along the front edge of the casing (the edge which is inserted into the disk drive) and thus covers and uncovers the magnetic head opening.
In one such magnetic disk cartridge, the shutter is forced into the closed position by a spring and is opened by a shutter opening pin which is provided in the disk drive and slides the shutter into the open position, overcoming the force of the spring when the cartridge is loaded into the drive.
An example of such a magnetic disk cartridge is shown in FIG. 2A. In FIG. 2A, reference numerals 2, 4, 6, 8 and 10 respectively denote the shutter opening pin, the magnetic disk, the casing, the magnetic head opening and the shutter. The shutter 10 can be slid along the front edge 6a of the casing 6 and is forced by a spring (not shown) or the like in the direction of arrow A into the closed position, in which it covers the magnetic head opening 10. Thus the shutter 10 is held in the closed position when the magnetic disk cartridge is free. A cutaway portion 12, which may be engaged with the shutter opening pin 2, is formed in the front edge portion 10a of the shutter 10. When the magnetic disk cartridge is loaded into a disk drive, the shutter opening pin 2 (which is provided in the disk drive as described above) is brought into engagement with the cutaway portion 12 as shown in FIG. 2A and is moved in the direction of arrow B, whereby the shutter 10 is moved to the open position and thus uncovers the magnetic head opening 8. When the movement of the shutter opening pin 2 in the direction of the arrow B is completed, the disk drive senses that the magnetic head opening 8 has been uncovered and proceeds to the next step.
However, as shown in FIGS. 3A and 3B, when the magnetic disk cartridge is inserted into the disk drive upside down, the shutter opening pin 2 will abut against the front edge of the casing 6, and since the front edge of the casing 6 is flat, the shutter opening pin 2 can slide along the front edge of the casing 6 in the direction of the arrow B without the shutter 10 trailing along. When the shutter opening pin 2 is moved in the direction of the arrow B, the disk drive may proceed to the next step irrespective of whether the shutter 10 has actually been opened. Furthermore, the magnetic disk cartridge is not in the correct position relative to the disk drive. Accordingly, the magnetic head in the drive may impact against the outer surface of the casing and can be damaged. Further, the magnetic disk cartridge also can be deformed or damaged since it is not being supported correctly.